"With frogs and toads, the external gills of the newly hatched tadpole are covered with a gill sac after a few days, and lungs are quickly formed. Front legs are formed under the gill sac, and hind legs are visible a few days later. Following that there is usually a longer stage during which the tadpole lives off a vegetarian diet. Tadpoles use a relatively long, spiral‐shaped gut to digest that diet.
Rapid changes in the body can then be observed as the lifestyle of the frog changes completely. The spiral‐shaped mouth with horny tooth ridges is resorbed together with the spiral gut. The animal develops a big jaw, and its gills disappear along with its gill sac. Eyes and legs grow quickly, a tongue is formed, and all this is accompanied by associated changes in the neural networks (development of stereoscopic vision, loss of the lateral line system, etc.) All this can happen in about a day, so it is truly a metamorphosis. It is not until a few days later that the tail is reabsorbed, due to the higher thyroxin concentrations required for tail resorption." Newts and Salamanders also go through a metamorphosis. Wikipedia online 7-12-19.
There are also classes of fish that undergo a form of metamorphosis: the Osteichthyes: Actinoopterygii ("ray Finned Fish like the Flounder) and Sarcopterygii ("Lobe-finned Fish" like the Coelocanth.)
Many biologists put the various groups of life forms in an evolutionary converging or diverging relatedness, but they could as well just be put into structure/function relationships and only associated genetically by progeny by directly observed sexual events. This is the problem with the evolutionary philosophy: it makes non-provable assumptions of relatedness. It is also true that the creation philosophy assumes distinct groups, except for observed variation, when classifying life forms. As a believer in the Biblical God, naming and classifying life forms is a God-given responsibility. See Genesis 2:19-20:
19 "And out of the ground the Lord God formed every beast of the field, and every fowl of the air; and brought them unto Adam to see what he would call them: and whatsoever Adam called every living creature, that was the name thereof.
20 And Adam gave names to all cattle, and to the fowl of the air, and to every beast of the field; but for Adam there was not found an help meet for him."
We, as parents, even have the responsibility of naming our children.